Hitherto, it has been attempted that fragrance materials (perfumes) or medical ingredients, etc., are encapsulated in microcapsules, prolonged their effects by being incorporated in products. In particular, one of important properties of fabric treatment products, cosmetics and detergents is to impart fragrance to clothes or human body, and therefore there is an increasing demand for products having a high persistence of fragrance.
Under these circumstances, there have been conventionally made intense studies on synthesis of the microcapsules by a sol-gel method.
For example, JP 2007-500590A aims at enjoying a benefit of a light-absorbing capability of sunscreens while substantially isolating the sunscreens, in particular, sunscreen active ingredients, from living tissues, and discloses microcapsules having a core material encapsulated within a microcapsule shell, the core material including an active ingredient, wherein the microcapsule shell includes an inorganic polymer constituted of polymerized precursors which is obtained by in-situ polymerization of the precursors, and the concentration of the core material based on a total weight of the microcapsules is not less than 95% w/w.
JP 2003-534249A discloses a therapeutic or cosmetic composition capable of stabilizing an active ingredient and delivering the ingredient which includes a plurality of microcapsules having a core-shell structure, wherein the microcapsules have a diameter of approximately 0.1 to 100 μM, wherein each core includes the active ingredient and is encapsulated within a microcapsule shell, and wherein the shell is constituted of an inorganic polymer obtained by a sol-gel process, and the microcapsule shell protects the active ingredient prior to topical application and releases the active ingredient from the microcapsules after topical application.
US 2010/0143422A aims, for example, at improving delivery of fragrance materials for various personal care products, and discloses a process for preparing microcapsule particles containing an active material in a core, the process including the steps of mixing a sol-gel precursor and an active material (in particular, essential oil); cooling the obtained mixture; then cooling a surfactant aqueous solution; adding the mixture of the sol-gel precursor and essential oil to the surfactant aqueous solution; emulsifying the resulting mixture; adding a defoamer to the emulsified mixture; and curing the mixture to form the microcapsule particles.